A flat-panel detector of said type usually has an amorphous silicon (aSi) flat panel that is subdivided into individual pixel arrays and of which at least a subarea is provided with a photo-active coating forming the scintillator layer. Said photo-active coating converts impinging x-rays into light pulses which are then detected by a semiconductor sensor assigned to the respective pixel array and forwarded as an electrical signal to a readout amplifier. Each of the pixel arrays arranged in lines and columns has a semiconductor sensor of said type. The individual pixel arrays form a matrix array.
A plurality of readout amplifiers are usually provided which in turn have a plurality of channels, for example 120, for the respective columns of the matrix array. One column is therefore read out via each channel, this process taking place line by line, which is to say serially. The detected light intensity is aggregated in the individual semiconductor sensors during the time that elapses between two readout operations.